Great topic, Always Trying. I'm not over 50, but my style has changed quite a bit as I've transitioned into being married and part of the corporate culture. I've come to speculate that "dressing your age" isn't so much about wearing things that are "age appropriate"... it's more about the fact that as we age, we mature. We realize that we wore certain things because we were insecure, because we had a fantasy lifestyle, because we wanted a certain kind of attention... or is it just me? I used to wear all kinds of things that I would never wear now, and in a way, I consider them "too young" for me. "Too young" means that I'd consider myself a bit immature if I wore those things again, or I think I'd come across as immature.
For example, I got rid of most of my miniskirts once I realized that I just don't feel very comfortable in them. At one time, the excitement and novelty of showing that much leg overpowered the self-consciousness and discomfort that came with it. Over time, I came to value my own comfort more. Black fishnets are the same way... I used to wear them a lot, but I came to realize that I cared a great deal about being able to get along with everyone, and the fishnets seemed to be getting in the way. There was a time when I was idealistic enough to think that it didn't matter how I dressed, and that it wouldn't affect how I was treated. That time has passed... I now value my sense of security more than proving I have the right to come across however I wish. To my mind, most of the things on your list of don'ts are widely
associated with communicating sexual availability... and I think that
many of us choose to avoid sending that message as we mature. There are a lot of things I've purged from my closet because I realized that my values had changed, or had become clearer to me. It's not that I won't wear a halter top, but I probably won't wear the one that's covered in sequins. To me, "dressing too young" feels very similar to "dressing to stand out a great deal"... as I've grown older, I've grown more comfortable in my own skin, and I don't feel that I need or want certain kinds of attention any more.
I think that as long as you have a clear sense of who you are, and you know why you like the things that you do, there's no need to ban any given item from your closet... regardless of age. It's just important, I think, to be honest with ourselves about how we come across... not only to ourselves, but to those who interact with us. And for some people, perceiving social friction or censure might not feel as difficult as it has been for me... in which case I'm not sure that anything is off limits.